Capturing of images, and in particular video images, is performed in a variety of applications. For example, some remote control applications transfer video frames from a remotely-controlled computer to a controlling computer. Some of these applications also transfer mouse and keyboard signaling from the controlling computer to the controlled computer. Such remote control applications are often referred to as keyboard-video-mouse (KVM) applications.
Remote frame buffer (RFB) is an exemplary open-source protocol used for remotely interacting with a computer. Virtual Network Computing (VNC) is an exemplary remote control software package, offered by RealVNC Ltd. (Cambridge, England), that uses the RFB protocol. Details regarding RFB and VNC are available at www.realvnc.com.
Some remote control applications capture and process video frames in the controlled computer. For example, U.S. Patent Application Publication 2004/0083256 A1, whose disclosure is incorporated herein by reference, describes a system for real-time image transmission monitoring for use in a network system connecting a server and a client. A video graphics array (VGA) signal-gathering module gathers first and second frames from the client. Each frame is divided into a plurality of sub-frames and each sub-frame is numbered. Then, the contents of sub-frames having the same number in the first and second frames are compared, and the content of the variation sub-frame in the second frame and its corresponding number are output to the server if the contents are different.
U.S. Pat. No. 6,304,895, whose disclosure is incorporated herein by reference, describes a method and system for remotely accessing and controlling a target switch and/or a target computer using a target controller. The video information captured by the target controller is analyzed and compressed in order to reduce network traffic between the target controller and a controlling computer. U.S. Patent Application Publication 2005/0114894 A1, whose disclosure is incorporated herein by reference, describes a remote network management system for coupling a series of remote serial devices, servers and computers to one or more user workstations.
U.S. Patent Application Publication 2005/0105608 A1, whose disclosure is incorporated herein by reference, describes a method and apparatus for transmitting video signals from a remote computer to a local computer over a network. Signals from the remote computer are received, digitized, conditioned and compressed for efficient transmission over the network connection. The method and apparatus also utilize a cache of recently-transmitted video to further decrease the data needed for transmission of the signals. The conditioning and caching use frame buffers of video signals that are divided into cells to reduce noise in the image, and to limit the portions of the video signals that must be transmitted.
Several vendors offer hardware and/or software KVM solutions, such as KVM-over-IP solutions. Such vendors include, for example, Peppercom USA, Inc. (Tucker, Ga.) and Avocent Corp. (Huntsville, Ala.). Further details regarding these products can be found at www.peppercom.com and www.avocent.com, respectively.